1). Large quantities of H2 are needed in the petroleum and chemical
industries. The largest application of H2 is for the processing
("upgrading") of fossil fuels, and in the production of ammonia.The
key consumers of H2 in the petrochemical plant include
hydrodealkylation, hydrodesulfurization, and hydrocracking.

2).Hydrogen gas is used as ashielding gasinweldingmethods such asatomic hydrogen welding.

3). In more recent applications, hydrogen is used pure or mixed
with nitrogen (sometimes calledforming gas) as a tracer gas for minute leak detection.

4).Hydrogen is commonly used in power stations as a coolant in
generators due to a number of favorable properties that are a
direct result of its light diatomic molecules.